// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_BASE_ACCELERATORS_ACCELERATOR_MANAGER_H_
#define UI_BASE_ACCELERATORS_ACCELERATOR_MANAGER_H_

#include <list>
#include <map>
#include <utility>

#include "base/macros.h"
#include "ui/base/accelerators/accelerator.h"
#include "ui/base/ui_base_export.h"
#include "ui/events/event_constants.h"

namespace ui {

// The AcceleratorManger is used to handle keyboard accelerators.
class UI_BASE_EXPORT AcceleratorManager {
public:
    enum HandlerPriority {
        kNormalPriority,
        kHighPriority,
    };

    AcceleratorManager();
    ~AcceleratorManager();

    // Register a keyboard accelerator for the specified target. If multiple
    // targets are registered for an accelerator, a target registered later has
    // higher priority.
    // |accelerator| is the accelerator to register.
    // |priority| denotes the priority of the handler.
    // NOTE: In almost all cases, you should specify kNormalPriority for this
    // parameter. Setting it to kHighPriority prevents Chrome from sending the
    // shortcut to the webpage if the renderer has focus, which is not desirable
    // except for very isolated cases.
    // |target| is the AcceleratorTarget that handles the event once the
    // accelerator is pressed.
    // Note that we are currently limited to accelerators that are either:
    // - a key combination including Ctrl or Alt
    // - the escape key
    // - the enter key
    // - any F key (F1, F2, F3 ...)
    // - any browser specific keys (as available on special keyboards)
    void Register(const Accelerator& accelerator,
        HandlerPriority priority,
        AcceleratorTarget* target);

    // Unregister the specified keyboard accelerator for the specified target.
    void Unregister(const Accelerator& accelerator, AcceleratorTarget* target);

    // Unregister all keyboard accelerator for the specified target.
    void UnregisterAll(AcceleratorTarget* target);

    // Activate the target associated with the specified accelerator.
    // First, AcceleratorPressed handler of the most recently registered target
    // is called, and if that handler processes the event (i.e. returns true),
    // this method immediately returns. If not, we do the same thing on the next
    // target, and so on.
    // Returns true if an accelerator was activated.
    bool Process(const Accelerator& accelerator);

    // Returns the AcceleratorTarget that should be activated for the specified
    // keyboard accelerator, or NULL if no view is registered for that keyboard
    // accelerator.
    AcceleratorTarget* GetCurrentTarget(const Accelerator& accelerator) const;

    // Whether the given |accelerator| has a priority handler associated with it.
    bool HasPriorityHandler(const Accelerator& accelerator) const;

private:
    // The accelerators and associated targets.
    typedef std::list<AcceleratorTarget*> AcceleratorTargetList;
    // This construct pairs together a |bool| (denoting whether the list contains
    // a priority_handler at the front) with the list of AcceleratorTargets.
    typedef std::pair<bool, AcceleratorTargetList> AcceleratorTargets;
    typedef std::map<Accelerator, AcceleratorTargets> AcceleratorMap;
    AcceleratorMap accelerators_;

    DISALLOW_COPY_AND_ASSIGN(AcceleratorManager);
};

} // namespace ui

#endif // UI_BASE_ACCELERATORS_ACCELERATOR_MANAGER_H_
